The Antibacterial Effect of the Films Coated with the Layers Based on Uncaria tomentosa and Formitopsis betulina Extracts and ZnO Nanoparticles and Their Influence on the Secondary Shelf-Life of Sliced Cooked Ham

Microbial surface contamination of the cooked ham sliced by shop assistants has an influence on its potential secondary shelf-life. Active packaging may be the solution. The first goal of the work was to obtain coatings based on Formitopsis betulina and Uncaria tomentosa extracts (separately), with the addition of nanoparticles of ZnO (as a synergetic agent to increase plant extracts' antimicrobial effectiveness), that could be active against selected bacterial strains. Another aim of the work was to determine the influence of obtained active layers on microbial purity and texture of the samples. The results of the study demonstrated that the layers containing F. betulina or U. tomentosa extracts with the addition of ZnO nanoparticles inhibited Staphylococcus aureus, Bacillus atrophaeus, and Escherichia coli growth completely and decreased the number of Pseudomonas syringae cells. Analyzing microbial purity of sliced cooked ham portions after storage, it was observed that the active packaging based on U. tomentosa extracts had a greater influence on the total count than the coatings containing F. betulina extracts and that both active packaging materials affected the microbial purity of the cooked ham. Analyzing the textural parameter changes after 48 h of storage, a decrease in the gumminess, chewiness and cohesiveness values was noted, but only for the ham portions stored in bags covered with the coating based on U. tomentosa. The effectiveness of the active packaging on textural parameters after 96 h of storage was not noticed.